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Date:   Tue, 11 Apr 2023 15:15:40 +0200
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Subject: Re: [PATCH 0/6] Initial Rust V4L2 support
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To:     Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc:     Daniel Almeida <daniel.almeida@collabora.com>, wedsonaf@gmail.com,
        ojeda@kernel.org, mchehab@kernel.org, hverkuil@xs4all.nl,
        rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-media@vger.kernel.org, kernel@collabora.com
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From:   Hans Petter Selasky <hps@selasky.org>
In-Reply-To: <CANiq72mv2uYe1x6cy4zUq8XHhAZcYYpt6hVXMG4yQZeqw1kY7Q@mail.gmail.com>
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On 4/11/23 14:36, Miguel Ojeda wrote:
> On Tue, Apr 11, 2023 at 11:52 AM Hans Petter Selasky<hps@selasky.org>  wrote:
>> Assume you need to update both the kernel and the rust compiler at the
>> same time. How do you do that? In the binary download case you have two
>> machines. One to build rust and one to build the kernel, so it is
>> technically not possible?
> I don't understand the problem -- you can build (or download) new
> toolchains without changing the kernel, and you can keep several
> kernels and several toolchains installed, too.
> 

Hi Miguel,

What I'm saying is a bit difficult to get about right off the bat.

 >you can build (or download) new toolchains without changing the kernel

Yes, most of the time, but not always. Let me rephrase it:

If you cannot build a new toolchain without a new kernel.

And:

You cannot build a new kernel without a new toolchain.

Then you are stuck forever to build a new toolchain and kernel? Do you 
agree?

Or you can say, someone else needs to deal with it, but then you have a 
single point of failure.

It's like the next version of the Rust compiler depends on the previous 
version of the Rust compiler.

But now you have (Version of Linux and version of Rust) depends on 
(Version of Linux and version of Rust).

So in order to upgrade either Linux or Rust, you may be forced to go 
through multiple, upgrade kernel, reboot, upgrade rust, build kernel, 
reboot and so on.

And that is an annoying complication when upgrading a system.

--HPS